The Need

Optical polarization controllers and rotators are necessary components to control optical polarization in bulk bench-scale optics. Current approaches to achieve on-chip polarization control on a chip include asymmetric gratings, waveguides with asymmetric slanted sidewalls, dual core waveguides with asymmetric axes, waveguides with asymmetric trenches, triple waveguide couplers, and bi-layer slots. These current methods suffer from several drawbacks:

1. They are static because they rotate the polarization by only a fixed amount. Rotation angles vary among approaches and can be as low as 39 degrees, corresponding to TE-TM conversion efficiencies of 40%. Currently, an on-chip tunable polarization rotator in silicon does not exist.
2. They rely on asymmetric geometries with impedance mismatches resulting in degradation of insertion loss.
3. They exhibit wavelength dependent loss because they rely on periodic structures or mode coupling.

The Technology

Researchers at The Ohio State University, led by Dr. Ronald Reano, have developed an on-chip tunable polarization rotator which can dynamically control the optical polarization in photonic integrated circuits. The invention replaces widely used bulk polarization controllers that are on the dimensional scale of inches with a chip-scale polarization controller that is on the dimensional scale of micrometers. This allows the control of optical polarization on a chip for sensing, communications, and computing applications based on miniature photonic integrated circuits. When implemented using CMOS compatible materials, the technology is suitable for mass production.

Commercial Applications

• Photonic integrated circuits: sensing, communications, and computing

Benefits/Advantages

• On the dimensional scale of micrometers
• Has a rotation angle equal to 60 degrees
• Compatible with mass production